Heart failure means that the heart muscle has lost its power to do the work it needs to do.  The heart still functions, but not as effectively as it should.

Causes of heart failure include coronary heart disease, congenital heart disease, viruses, severe infection, muscular dystrophies, drugs, and chemicals naturally found in your body during and after pregnancy (it is uncommon, but it happens).

It is important to understand that for many, if not most, cases of cardiomyopathy, a specific cause may never be found.  This form of the condition is called primary or idiopathic cardiomyopathy. 

Secondary cardiomyopathy does have a specific cause.  Ischemic cardiomyopathy is caused by a chronic lack of oxygen to the heart muscle because of coronary artery disease.

Non-ischemic cardiomyopathy is not caused by coronary artery disease, but by other causes.  Those causes include:

• Congenital heart disease, that is, heart problems that have been inherited
• Viral infections
• Bacterial infections
• Muscular dystrophies
• Dystrophy is a general term for the progressive degeneration or abnormal development of tissues or organs
• Drug abuse, especially of cocaine, amphetamines, and antidepressants
• Certain chemicals found in the body during and after pregnancy
• Alcohol abuse
• Chronic untreated high blood pressure (hypertension)
• Problems with metabolism, such as thyroid disease or diabetes
• Uncontrolled diabetes increases the risk of developing coronary artery disease and hypertension, both of which can lead to cardiomyopathy
• Problems with heart valves
• Chronic rapid heart rate
• Inadequate nutrition, especially of essential vitamins and minerals
• Morbid obesity
• Genetic disorders

Cardiomyopathy can be diagnosed through a variety of tests, including:

• Echocardiogram: sound waves are bounced off the heart to produce still and moving images of it (similar to ultrasound imaging used with pregnant women to produce images of fetuses)
• Cardiac catheterization: in this more invasive test, the doctor inserts a small tube (catheter) through a blood vessel, running it into the heart, to remove a tiny sample for examination in the laboratory (biopsy) or to inject dye into the heart chambers to measure cardiac function, measure pressures produced by the heart muscle, examine blood flow through the heart, and examine the coronary arteries.
   
  You can find detailed information about these and other diagnostic techniques on the American Heart Association's website.